We just finished a migration from Exchange 2003 to 2010 (old servers have been removed from the org, wiped, etc) and most everything seems to be working. I do have an issue with Outlook 2003 users - they cannot view the Free/Busy information of other users. Running outlook with /cleanfreebusy results in a dialog stating that outlook is unable to clean the free/busy information on the server. Upgrading the user to Outlook 2010 had no impact. Users who were on Outlook 2007/2010 prior to shutting down the Exch 2003 machines do not seem to be affected.
I did find a KB article (http://support.microsoft.com/kb/945602/en-us) that seems to be relevant, but there already is a replica for the Exch2010 pub folder. However, it still has the old Exch org listed in free/busy... is this a problem? Should I just add a replica to that one? Should it be deleted?
get-publicfolder -Identity "\NON_IPM_SUBTREE\SCHEDULE+ FREE BUSY" -Recurse | fl name,Replicas
Name : SCHEDULE+ FREE BUSY
Replicas : {}
Name : EX:/o=ExchOrgName/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)
Replicas : {Public Folder Database 1878261148}
Name : EX:/o=ExchOrgName/ou=OldAdminGroup
Replicas : {}